Rotor for torque sensor

ABSTRACT

Disclosed is a rotor for a torque sensor configured to improve a mechanical coupling force with respect to a jig in a process of adjusting a torque center, thus enabling a fine adjustment, the rotor including a rotor body having a sleeve coupled to a rotating shaft and a yoke protruding from an outer circumference of the sleeve, a ring-shaped magnet coupled to an outer circumference of the yoke, and an anti-slip structure formed on the rotor body and partially coming into contact with a jig during a rotating process for adjusting a torque center, thus inhibiting slipping between the rotor body and the jig when a rotating force is transmitted, so that slipping between the jig and the rotor body is inhibited to enable precise transmission of the rotating force whereby accuracy is improved during fine adjustment of the torque center.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of prior U.S. patentapplication Ser. No. 14/280,367 filed May 16, 2014, which is aContinuation application of prior U.S. patent application Ser. No.13/923,865 filed Jun. 21, 2013 (now U.S. Pat. No. 8,776,618), which is aContinuation application of prior U.S. patent application Ser. No.13/455,591 filed Apr. 25, 2012 (now U.S. Pat. No. 8,584,532), whichclaims priority under 35 U.S.C. §119 to Korean Application No.10-2011-0038654 filed on Apr. 25, 2011, whose entire disclosures arehereby incorporated by reference.

BACKGROUND

1. Field

The present invention relates generally to a rotor for a torque sensorand, more particularly, to a rotor for a torque sensor, configured toimprove a mechanical coupling force with respect to a jig in a processof adjusting a torque center, thus enabling a fine adjustment.

2. Background

Generally, a vehicle is configured to change a driving direction bymanipulating a steering wheel connected to a wheel. However, ifresistance between the wheel and a road is large or there is an obstacleto steering, a manipulation force is decreased, thus making it difficultto rapidly manipulate. In order to solve the problem, a power steeringsystem has been used. Such a power steering system includes a power unitto manipulate the steering wheel, thus reducing a manipulation force.

In order for the power unit to assist in manipulating the steeringwheel, it is necessary to measure torque acting on a steering shaft.Thus, several types of devices are used to measure torque of thesteering wheel. Among them, a device detecting torque by measuring amagnetic field relative to a magnet coupled to the steering shaft hasbeen widely used because it is more economical.

A general steering structure includes an input shaft to which a steeringwheel is coupled, an output shaft coupled to a pinion engaging with arack bar of a wheel, and a torsion bar connecting the input shaft andthe output shaft.

If the steering wheel rotates, a rotating force is transmitted to theoutput shaft, and the wheel changes its direction by interaction betweenthe pinion and the rack bar. Here, the larger resistance is, the morethe input shaft rotates. Hence, the torsion bar is twisted. A degree towhich the torsion bar is twisted is measured by the torque sensor usingthe magnetic field.

When the steering wheel is not manipulated, the torque sensor maintainsa central position. If a set center is erroneous, there occurs adifference in auxiliary steering force between left and right sidesduring a manipulation of the steering wheel. Thus, as for the powersteering system, it is very important to adjust the center of the torquesensor.

FIG. 1 is a perspective view showing a conventional rotor for a torquesensor.

A rotor 1 having a magnet 2 is coupled to an input shaft of a steeringsystem, and a stator (not shown) is coupled to an output shaft.

If the torsion bar is twisted by a difference in rotation amount betweenthe input shaft coupled to the rotor 1 and the output shaft coupled tothe stator, the magnet 2 and the stator rotate relative to each other.At this time, opposite surfaces between the magnet 2 and the stator arechanged, so that a magnetization value is changed, and thereby torquemay be measured using the change in magnetization value.

The rotor 1 includes a sleeve 4 coupled to an outer circumference of theinput shaft, and a yoke 3 coupled with the sleeve 4 to allow the magnet2 to be coupled to an outer circumference thereof.

In order to adjust the center of the torque sensor, there has been useda method of holding a predetermined portion on the outer circumferenceof the sleeve 4 by a jig and then rotating the rotor 1 by a frictionalforce.

However, such a method is problematic in that the jig rotates the outercircumference of the sleeve by the frictional force, so that there is arelatively strong possibility that the jig will slip from the sleeve,and it is difficult to finely adjust the center.

The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a rotor for a torque sensor, capable of moreprecisely performing a center adjusting operation.

According to one aspect of this invention, there is provided a rotor fora torque sensor, the rotor comprising: a rotor body including a sleevecoupled to a rotating shaft, and a yoke protruding from an outercircumference of the sleeve; a ring-shaped magnet coupled to an outercircumference of the yoke; and an anti-slip structure formed on therotor body and partially coming into contact with a jig during arotating process for adjusting a torque center, thus inhibiting slippingbetween the rotor body and the jig when a rotating force is transmitted.Thus, slipping between the jig and the rotor body is inhibited to enableprecise transmission of the rotating force, so that accuracy is improvedduring fine adjustment of the torque center.

Further, the anti-slip structure may include a serration formed on anupper end of the yoke in a circumferential direction thereof, theserration coming into contact with a lower end of the jig during therotating process for adjusting the center, thus transmitting therotating force from the jig to the yoke. Thus, the jig is brought intocontact with the yoke, thus allowing the rotating force to be reliablytransmitted when the center is adjusted.

Further, the anti-slip structure may include a hole formed in the outercircumference of the sleeve, and a protrusion formed on the jig isinserted into the hole, thus transmitting the rotating force from thejig to the sleeve. Thus, the jig comes into contact with the sleeve,thus allowing the rotating force to be more reliably transmitted whenthe center is adjusted.

Further, the anti-slip structure may include a knurled portion formed onthe outer circumference of the sleeve, and the jig partially comes intocontact with the knurled portion of the sleeve, thus transmitting therotating force from the jig to the sleeve. Thus, a frictional forcebetween the sleeve and the jig is improved, thus allowing the rotatingforce to be reliably transmitted.

Further, the anti-slip structure may include a depression formeddownwards from an upper end of the sleeve, and a protrusion formed onthe jig is inserted into the depression, thus transmitting the rotatingforce from the jig to the sleeve. Thus, a mechanical coupling forcebetween the sleeve and the jig is excellent.

Meanwhile, according to another aspect of this invention, there isprovided a rotor for a torque sensor, the rotor comprising: a rotor bodycoupled to a rotating shaft; a ring-shaped magnet disposed to protrudeto an outer circumference of the rotor body; and an anti-slip structureformed on the rotor body, wherein during a rotating process foradjusting a torque center, a jig comes into contact with the outercircumference of the rotor body or an upper portion of the magnet, andthe anti-slip structure is formed on a surface making contact with thejig, thus inhibiting slipping between the jig and the rotor body. Thus,a frictional force between contact portions of the jig and the rotor isimproved, so that the accuracy of a center adjustment is improved.

A rotor for a torque sensor according to the present inventionconstructed as described above is advantageous in that a frictionalforce is increased at a portion coupled with a jig when a center of therotor is adjusted, thus providing various structures that enable precisetransmission of a rotating force, and thereby permitting a fineadjustment of the torque center, therefore improving operationalreliability of a steering system.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a perspective view showing a conventional rotor for a torquesensor;

FIG. 2 is a perspective view showing a rotor for a torque sensoraccording to the present invention;

FIG. 3 is a perspective view showing a coupling of a jig and a rotor fora torque sensor according to an embodiment of the present invention; and

FIG. 4 is a perspective view showing a coupling of a jig and a rotor fora torque sensor according to another embodiment of the presentinvention.

DETAILED DESCRIPTION

Hereinafter, a rotor for a torque sensor according to the preferredembodiment of the present invention will be described in detail withreference to the accompanying drawings.

FIG. 2 is a perspective view showing a rotor for a torque sensoraccording to the present invention.

A magnet 20 is shaped like a ring, and is generally coupled to an outercircumference of an input shaft of a steering system to be rotated alongwith the input shaft.

Further, a stator (not shown) is connected to an output shaft to berotated along with the output shaft.

It can be understood that torsion occurs when there is a difference inrotation amount between the input shaft and the output shaft due toresistance of a wheel. The difference is measured using a magnetic fieldas described above. Of course, the magnet 20 may be connected to theoutput shaft, and the stator may be connected to the input shaft.

The rotor 10 includes a rotor body and the ring-shaped magnet 20. Therotor body includes a ring-shaped yoke 30 that protrudes outwards from alower end of a sleeve 40 taking a shape of a hollow cylinder. The magnet20 is coupled to an outer circumference of the rotor body. To be morespecific, the magnet 20 is coupled to an outer circumference of the yoke30.

As described above, an inner circumference of the sleeve 40 is connectedto a rotating shaft of the steering system to be rotated along with therotating shaft.

Further, the yoke 30 is coupled to the sleeve 40 to support the magnet20 and thereby rotate along with the sleeve 40. However, the yoke 30 maybe integrated with the sleeve 40.

Preferably, the magnet 20 comprises two or more magnet segments that areto be connected to each other. To be more specific, a plurality ofarc-shaped magnet segments forms the ring-shaped magnet 20.

The rotor 10 is coupled to the rotating shaft of the steering system byfitting the rotor 10 over the rotating shaft starting from a lowerportion of the sleeve 40, and a torque center is adjusted by anadditional device, a jig.

According to the present invention, the rotor body has a shape to allowrotating power to be reliably transmitted between the jig and the rotor10, thus inhibiting slipping between the rotor body and the jig when thetorque center is adjusted, and thereby enabling a precise adjustment.Such a shape may be implemented by various embodiments of anti-slipstructures, for example, a structure for increasing a frictional forcebetween contact portions, such as a serration or a micro groove, or astructure for providing a mechanical coupling force, such as a hole or arecess.

Thus, as a first embodiment for increasing a rotating frictional force,a serrated portion 31 is formed on an upper end of the yoke 30.

The serrated portion 31 is circumferentially formed on an upper surfaceof the yoke 30 protruding outwards from a lower end of the sleeve 40,thus having an uneven shape. It is preferable that the uneven shape be awedge shape to allow the serrated portion 31 to be easily coupled to thejig.

In this case, a lower end of the jig is brought into contact with anupper end of the uneven serrated portion 31 to transmit a rotatingforce.

Further, as a second embodiment for increasing a frictional force, anuneven portion may be formed on the upper surface of the yoke 30.

The uneven portion may be formed by fine line-shaped grooves, or maycomprise a single protrusion or a plurality of protrusions. In anexample of FIG. 4, the uneven portion is formed by a plurality ofdiagonal line-shaped grooves.

Similarly to the first embodiment, the second embodiment provides africtional force when a lower end of a jig comes into contact with theupper surface of the yoke 30.

Further, as a third embodiment for increasing a frictional force, a hole42 is formed in a side surface of the sleeve 40.

Preferably, the hole 42 is formed in the side surface of the sleeve 40making contact with the jig, and a protrusion is formed on a portion ofthe jig to be fixedly inserted into the hole 42.

According to a shape of the jig, a single hole or a plurality of holesmay be formed in the side surface of the sleeve 40.

Meanwhile, the hole 42 may be replaced by a recess, a fine line-shapedgroove, a single protrusion or a plurality of protrusions.

Further, as a fourth embodiment for increasing a frictional force, adepression may be formed in an upper end of the sleeve 40.

The depression is depressed downwards from the upper end of the sleeve40. In this case, the jig comes into contact with the upper end of thesleeve 40 and includes a protrusion that may be inserted into thedepression, thus maximizing a frictional force therebetween.

The above embodiments for increasing the frictional force may beselectively applied, but two or more embodiments may combine with eachother.

For example, both the serrated portion 31 of the yoke 30 and the hole 42of the sleeve 40 may be formed, and the jig may be disposed to be incontact with both the upper surface of the yoke 30 and the side surfaceof the sleeve 40. In this case, since a frictional force between contactsurfaces of the rotor 10 and the jig is maximized, a center adjustingoperation can be precisely performed.

FIG. 3 is a perspective view showing a coupling of a jig and a rotor fora torque sensor according to an embodiment of the present invention.

While the torque center of the rotor for the torque sensor is adjusted,the lower end of the jig 50 comes into contact with the upper surface ofthe yoke 30 in a state in which the rotor 10 is coupled to an outercircumference of the rotating shaft.

Since the serrated portion 31 is formed on the upper surface of the yoke30 and a serrated portion is also formed on the lower end of the jig 50to correspond to a shape of the serrated portion 31, a rotating forcecan be precisely transmitted between the yoke 30 and the jig 50.

FIG. 4 is a perspective view showing a coupling of a jig and a rotor fora torque sensor according to another embodiment of the presentinvention.

Unlike the embodiment of FIG. 3, a jig 51 comes into contact with theside surface of the sleeve 40.

A diagonal line-shaped knurled portion 43 is formed on the side surfaceof the sleeve 40. The knurled portion 43 increases a frictional force ata contact portion between the sleeve 40 and the jig 51, thus allowing arotating force to be precisely transmitted.

Of course, as described above, the knurled portion 43 may be replaced bya hole 42 or a protrusion.

According to the above embodiment, the jig comprises two long bars.However, the jig may be selected from various shapes including one barand a ring, as long as it may transmit a rotating force to the rotor andadjusts the center.

The present invention provides various structures for preciselytransmitting a rotating force by increasing a frictional force at aportion coupled with a jig when a center of a rotor of a torque sensoris adjusted. Thus, a fine adjustment of the torque center is possible.This improves operational reliability of a steering system.

The present invention has been described with reference to embodimentsand the accompanying drawings. However, it is to be understood that thescope of the invention is not limited by the specific embodiments anddrawings except as defined in the appended claims.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A rotor for a torque sensor comprising: a rotorbody comprising a sleeve having a first outer circumference and a yokehaving a second outer circumference; a magnet provided around the secondouter circumference of the yoke; a serrated portion having a pluralityof serrations being arranged in a circumferential direction of the rotorbody, wherein each of the plurality of serrations extend in a radialdirection of the rotor body.
 2. The rotor of claim 1, wherein a width ofthe serrated portion is smaller than a width of the magnet, and thewidths of the serrated portion and the magnet are lengths in an axialdirection of the rotor body.
 3. The rotor of claim 1, wherein aprotruding direction of the plurality of serrations is parallel to anaxial direction of the rotor body.
 4. The rotor of claim 3, wherein theserrated portion is disposed at a higher position than the magnet in theprotruding direction of the plurality of serrations.
 5. The rotor ofclaim 1, wherein the sleeve, yoke, magnet and serrated portion have acircular shape.
 6. The rotor of claim 5, wherein a center of the sleeve,yoke, magnet and serrated portion are aligned in a direction of a shaftprovided through an inner circumference of the sleeve and the yoke. 7.The rotor of claim 1, wherein the second outer circumference of the yokeis greater than the first circumference of the sleeve, wherein thedifference in the first outer circumference of the sleeve and the secondouter circumference of the yoke results in a ledge being provided on theyoke, and the serrated portion is provided on the ledge.
 8. The rotor ofclaim 1, wherein the serrated portion has first and second surfaces, theplurality of serrations are provided on the first surface and the secondsurface is in contact with the yoke.
 9. The rotor of claim 1, whereinthe yoke is integrated with the sleeve.
 10. The rotor of claim 1,wherein the magnet comprises a plurality of segmented arc-shapedmagnets.
 11. The rotor of claim 1, wherein at least one hole is providedon a side surface of the sleeve.
 12. The rotor of claim 1, wherein theserrated portion is configured for coupling to a jig.
 13. A torquesensor comprising: a stator coupled to a first shaft; and a rotorcoupled to a second shaft and disposed in the stator, wherein the rotorcomprises, a rotor body comprising a sleeve having a first outercircumference and a yoke having a second outer circumference; a magnetprovided around the second outer circumference of the yoke; a serratedportion having a plurality of serrations being arranged in acircumferential direction of the rotor body, wherein each of theplurality of serrations extend in a radial direction of the rotor body.14. The torque sensor of claim 13, wherein a width of the serratedportion is smaller than a width of the magnet, and the widths of theserrated portion and the magnet are lengths in an axial direction of therotor body.
 15. The torque sensor of claim 13, wherein a protrudingdirection of the plurality of serrations is parallel to an axialdirection of the rotor body.
 16. The torque sensor of claim 15, whereinthe serrated portion is disposed at a higher position than the magnet inthe protruding direction of the plurality of serrations.
 17. The torquesensor of claim 13, wherein the serrated portion has first and secondsurfaces, the plurality of serrations is provided on the first surfaceand the second surface is in contact with the yoke.
 18. The torquesensor of claim 13, wherein the second outer circumference of the yokeis greater than the first circumference of the sleeve, wherein thedifference in the first outer circumference of the sleeve and the secondouter circumference of the yoke results in a ledge being provided on theyoke, and the serrated portion is provided on the ledge.
 19. The torquesensor of claim 13, wherein at least one hole is provided on a sidesurface of the sleeve.
 20. The torque sensor of claim 13, wherein theserrated portion is configured for coupling to a jig.